ref: f02c92a5fb2d18e1248a67b15cd2ec7dcea2b4d7
dir: /sys/src/libc/9sys/privalloc.c/
#include <u.h>
#include <libc.h>
static Lock privlock;
extern void **_privates;
extern int _nprivates;
void **
privalloc(void)
{
void **p;
lock(&privlock);
if(_nprivates > 0)
p = &_privates[--_nprivates];
else
p = nil;
unlock(&privlock);
return p;
}